10 BULLETIN 991, U. S. DEPARTMENT OF AGRICULTURE. 



Kotation No. 7 is barley, corn, and oats all on spring plowing. The 

 oats on disked corn ground in rotation No. 4 have outyielded the oats 

 on the plowed corn ground in this rotation in 6 out of 13 years, the 

 average increase for the 13 years being 1.1 bushels per acre. 



In all the comparisons of disked and plowed corn ground results in 

 the year 1912 stand out as markedly unfavorable to the disking. In 

 all but one of the comparisons the experience of 1915 is also unfavor- 

 able to the practice. These were both years of abundant rainfall and 

 heavy production. 



In the tests on section 9 the disked corn ground outyielded the 

 plowed land in 1918 and 1919, but in 1917 the reverse was true. 



The evidence seems quite conclusive that while individual years 

 may favor either plowing or not plowing the corn ground, the aver- 

 age of a series of years is in favor of seeding without plowing. This 

 means in practice a strong recommendation against plowing corn 

 ground before seeding, on account of the cost and the time consumed 

 in plowing. 



The effect on the crops that follow is not considered in detail, as 

 it appears to be negligible. 



CORN GROUND COMPARED WITH SMALL-GRAIN STUBBLE FOR 

 WHEAT AND OATS. 



Three 3-year rotations. Nos. 1, 2, and 3. have wheat on corn ground 

 and oats following wheat, while the 3-year rotations, Nos. 4 and 9, 

 have the same crops, but with the oats on corn ground and the wheat 

 following oats. 



The average yield in these rotations of wheat following corn is 

 18.4 bushels, and following oats 14.5 bushels per acre, an advantage 

 of 3.9 bushels per acre in favor of the corn ground. The yield on 

 corn ground has exceeded that on oat stubble every year since the 

 experiments were started. 



The oats following corn in rotations, Nos. 4 and 9, show an average 

 increase over the oats following wheat in rotations Nos. 1, 2, and 3 

 of only 1 bushel per acre. In six years the higher yield has been fol- 

 lowing corn, and in seven years it has been following wheat. On 

 section 9 for the 3-year period, from 1917 to 1919, inclusive, the same 

 rotations have shown an increase of 1.2 bushels for wheat on corn 

 ground, and 5.3 bushels for oats on corn ground. 



These results show a rather decided advantage of corn over small 

 grain as a crop to precede small grain. They indicate very clearly 

 that in a combination of wheat, oats, and corn the wheat should fol- 

 low the corn and the oats follow the wheat. 



GRAIN STUBBLE COMPARED WITH FALLOW. 



Several closely and directly comparable experiments afford data 

 for a study of the relative merits of fallow and cropped land as a 

 preparation for a crop. 



